Start with a glass. Now, fill it with as much water as you want in it. The glass is now as full as you want it to be.
Every positive adds water to the glass.
Every negative removes water from the glass.
Every positive has an equal and opposite negative.
Every negative has an equal and opposite positive.
The level of water in the glass can never change.
Therefore, the glass is exactly as full as you want it to be.
How full is YOUR glass?